Hollow metal propeller blade and method of making the same



HOLLOW METAL PROPELLER BLADE AND METHOD 0F MAKING THE SAME Feb. 1l, 19414'. M. H. ADAMEm-:LL

Filed Jan. lO, 1938 2 Sheets-SheeI l Feb. 11, 1941. M. H. DAME-REU.

HOLLOW METAL PROPELLER BLADE AND METHOD OE MAKING THE SAME Filed Jan. 1,0, 1938 2 Sheets-Sheet 2.

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Patented Feb. l1, 1941 UNITED STATES PATENT OFFICE HOLLOW METAL PROPELLER BLADE AND METHOD F MAKING THE SAME Application January 10, 1938, Serial No. 184,205

4 Claims.

This invention relates to metalpropeller blades for aircraft engines and more particularly to steel or alloy blades formed in part by. forging V operations.

5 It is the` general object of my invention to provide an improved construction of hollow metal propeller blade and an improved method of making the same, which method includes one or more forging operations.

A further object is to provide a hollow metal propeller blade which is longitudinally and integrally reenforced in a novel and e'ective manner.

My invention further relates to arrangements and combinations of parts and to certain ordered steps of procedure which will be hereinafter de;- scribed and more particularly pointed out in the appended claims.

Throughout the specification and in the claims,

2o the term metal is to be understood to include steel and also ferrous or other alloys having similar characteristics.

A preferred form of the invention is shown in the drawings, in which Fg. 1 is a plane view of my improved propeller bla e;

Figs. 2, 3 and 4 are sectional views, taken along the lines 2-2, 3-3 and 4-4 in Fig. lrespectively;

Fig. 5 is a .transverse sectional view of a. blank from which my improved propeller blade may be formed;

Figs. 6 and '7 .are sectional views showing cer-v tain steps in the formation of the propeller blade;

Fig. 8 is an enlarged detail sectional View to be described;

Fig. 9 is a similar view of a slight modification;

Fig. 10 is an enlarged partial plan view of the shank or hub portion of the blank shown in section in Fig. 5; i

Fig. 11 is a similar view of the tip of the blade blank;

5 Fig. 12 is a partial plan view similar to Fig. 11

but showing a slight modification;

Fig. 13 is a detail sectional view, taken along the line I3-l3 in Fig. 10; and

Fig. 14 is a transverse sectional view of a modified construction of blade.

Referring to the drawings, I have shown my invention as embodied in a steel propeller blade I5 of conventional external form but of hollow construction and provided with a longitudinally extending reenforcing rib. The cross section of the blade is progressively reduced toward the tip of theblade, as indicated by the successive sections in Figs. 2, 3 and 4 respectively, and the height of the reenforcing rib is correspondingly .and gradually reduced toward the tip. The blade 5 I5 has a shank or hub portion -I 1 of reenforced circular section.

Referring to Figs. 5, 10 and l1, I preferably form my improved propeller blade from a steel Ibillet, forged to a blankof the general shape indi- 10 cated in said figures, with a. double grooved hub portion 20 at one end, and with a. broad flat portion 2| having a rib 22 extending longitudinally thereof on one side and having additional ribs 23 and 24 formed on the opposite side of the j blank and opposed to longitudinal grooves 25.

The tip portion 26 (Fig. l) of the blank has a full thickness middle end portion 2': (Fig. 11) formed as a continuation of the rib 22 and has single-thick side end portions 28 adapted to be l folded over in hollow form, as will be described.

A slight variation of this construction is shown in Fig. 9, in which the edges of the outer portions of the blank are left square and the top of the rib 22a is recessed at the edges, as shown at 34.

After the formation and outlining of the blank as shown in Figs. 5, 10 and 11, a further forging or bending operation brings the outer edge portions 30 and Il of the blank to the position shown in Fig. 6. After this operation, the upper face of the middle portion of the blank (as viewed in Fig. 6), the inner faces of the edge portions 30 and 3l, and the sides and upper edge of therib 22 are machined, milled, ground or otherwise brought to a carefully finished and uniform sur face.

Cores C .and C (Fig. 7) of a metal ,alloy are then placed on the blank at each side of the iinished longitudinal rib 22 and the blank and cores t are heated to a `temperature such as 1200 F. at which the blank can be bent but at which the .alloy cores will not melt. The portions 30 and 3| are then folded downward over the cores C and C' and the blank is then subjected to press- 4f ing operations to bring it to the finished section shown in Fig. 7 and also in Figs. 2, 3 and 4.

After the blank has thus been accurately brought to the desired internal and external shape, the temperature is raised suiliciently as around l600 F. to melt the alloy cores C and C', and the core metal is drained oil' through the opening in the hub portion I1 of the propeller blade.

, It has been noted that the edges of the parts 1 30 and 3| (Fig. 8) are cut away to provide recesses 32. These recessed edges are welded or brazed to the upper edge of the rib 22, which rib thus constitutes a longitudinally extending re- 5 enforcement which positions and Asupports said parts 30 and 3|, with a single joint line 33 only appearing on the outside of the blade. l

The reenforcing rib 22 4is thus forged integral with one part of the propeller blade and is rigidly and permanently secured to the opposite parts thereof, which constitutes an exceptionally reliable construction.

The edges of the hub portion 2li-are similarly welded or brazed together, and the exterior s urfaces of the blade are then ground, polished and otherwise finished as desired. The blademay also vbe twisted to give it the desired helical pitch at some convenient point in theprocess, preferably before the edges of the parts 38 and 3| are secured to the rib 22.

In the form shown in Fig. 11, the edge portions 28 of the tip are folded over and secured to the thicker tip portion 21 along the `curved outlines 35 thereof, while in the modification 25 shown in Fig. 12 the curved edge portions 4l and 4l are secured to each otherV andthe straight outer edges 42 are secured to the rib 22 for the whole length of the blade.

I am thus able to provide a hollow propeller blade formed of steel or a strong weldable `:llerrous or other alloy, which propeller blade is formed with an integral reenforcing rib and with a, single longitudinal'line joint. There are no separate and possibly displaceable parts and the reenforcing rib is forged with the blade, as are also the reenforced edge portions. Consequently my improved hollow propeller blade possesses very great strength, and the possibility of failure due to internal defects is substantially elim- 40 inated.

In Fig. 14 `I have shown a construction which may be desirable for very long and correspondingly Wide propellers. The construction is the same as previously described, except that addi- Lional longitudinal reenforcing ribs 50 are provided at one or both sides of the mid-rib 5I. The side portions'52 and 53 of the curved face wall will be firmly secured to the ends of the additional ribs by welding, brazing or other suit- ;,0 able method.

Having thus described my invention andthe advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. 'I'he method of making a hollow metal prothereafter uniting the extreme outer edge portions of the forged blank to the upper ledge, of said first rib throughout the length of the propeller blade. 15

2 The method of making a hollow metal propeller blade which consists in forging a blank which is generally flat but which is provided witha longitudinally extended integral reenforcme. rib on one side thereof and with an addi- 2 tional 'integral rib at each side of said first rib, which' additional ribs are curved in the plane of the blank and variably spaced laterally from said first rib and positioned on the opposite side ofsaid blank from said iirst rib, providing said 25 blank with longitudinal grooves opposite said additional ribs, manipulating said blank so that Y said additional ribs form thickened edge portions of the completed propeller, finishing the surfaces of seid biangwmen win form the internal sur- 30 faces of saidv blade, and uniting the outer edge portions of the'fcrged blank to the upper'edge of said first rib throughout the length of the propeller blade.

3. A forged blank for forming a hollow metal 35 propeller blade tapering from an intermediate portion toward its ends, said blank being substantially flat and having an integral medial 1ongitudinal rib on one face, and two outer ribs on the other face of greater thickness than the 40 flat portion of the blank, said outer ribs being curved longitudinally to form the outline of the completed blade, and being sufficiently spaced fron the longitudinal edges of the blank and from the medial rib so that when the outer edge por- 45 tions 'of the blank are bent toward each other about the outer curved ribs the edges may contacttthe 'medial rib, the curved ribs providing reinforced edges in the completed blade.

4.=A forgedmetal propeller blade formed from '50 the blank defined in claim 3 by bending the outer edge portions of the blank toward each other to contact the medial rib, and uniting said edge portions and said rib.

' MARK H. DAMERELL. 55 

